Recurrent ascending aortic pseudoaneurysms: rare but a feared complication

Abstract

Presenting a case of recurrent ascending aortic pseudoaneurysms following emergency type A aortic dissection. It is a rare complication of aortic surgery but once diagnosed; especially in patients with suspected mycotic infection, it necessitates high-risk early surgical interventions.

Introduction

Good long-term outcomes following ascending aortic and root replacement surgery are well recognized both in routine as well as in the emergency conditions [1]. Complications like excessive bleeding, haematoma formation, pseudoaneurysms, coronary button stenosis, and kinking and prosthetic valve-related issues kept surgeons motivated to keep improving and innovating in this field. We are presenting a complicated surgically managed case of recurrent pseudoaneurysms following emergency type A aortic dissection repair.

Case report

A 73-year-old lady had cardiac arrest during swimming and was revived by giving cardiopulmonary resuscitation (CPR). Patient was otherwise fit and had medical history of hypertension and hypercholesteremia. Electrocardiogram (ECG)-gated cardiac tomogram (CT scan) showed mildly dilated ascending aorta with a large intra-mural haematoma extending from the sino-tubular junction (STJ) into the aortic arch vessels and in descending aorta. Extravasation of the blood was seen through the ascending aorta into the pericardial sac. Echocardiogram showed significant pericardial collection with normally functioning tricuspid aortic valve. Patient underwent emergency surgery and her ascending aorta (with hemi arch) was replaced using 32 Gelweave tube graft (Terumo, Australia). There was a tear seen near the STJ between non and right coronary cusp. Patient’s aortic root was not effaced, with normally working tri-leaflet aortic valve, and this was the reason that root was not replaced. Distal aortic anastomosis was performed without aortic cross clamp. Patient recovered well after the first surgery and remained active life post-surgery. Histology on the first occasion showed aortic dissection and haematoma. There were no suggestions of connective tissue disorder.

She had two admissions after the surgery with high-grade fever, which were treated with empirical antibiotics. All cultures were negative and radiological findings were within normal limits. Follow-up CT scan after 1 year showed a pseudoaneurysm of size 3 × 3.1 cm on the proximal aorta at the junction of non and right coronary cusp (Fig.1). Repeat scan within the next 2 weeks showed pseudoaneurysm expansion and widening of the neck. Redo sternotomy was performed and cardiopulmonary bypass (CPB) was established through right femoral artery and right atrial cannulation. The aorta was cross clamped and blood cardioplegia was given. On moderate hypothermia, pseudoaneurysm was dissected and excised. Defect on the aorta was patched using a tailored Dacron graft. Patient recovered well after the surgery and aortic tissue had no microbial growth on the microbiology examination.

Fig. 1.

Follow-up contrast CT scan (volume-rendered image): arrow showing pseudoaneurysm on the proximal aorta at the junction of non and right coronary cusp

After 1 month post-surgery, she was admitted in Medicine department with the diagnosis of “Pyrexia of Unknown Origin” (PUO). On this admission, her all cultures were negative, and she clinically recovered in a weeks’ time. At a 6-month follow-up, CT scan showed recurrence of pseudoaneurysm on the ascending aorta proximal to the graft suture line and lateral to the previously used patch (Fig. 2). The size of this pseudoaneurysm grew fast (2.8 × 2.1 cm to 3.4 × 3.8 cm with 2.1-cm neck within 10 days) and she became symptomatic soon. Patient was presented in emergency with a pulsating mass in the supra sternal area. Echocardiogram showed large aortic pseudoaneurysm and moderate aortic regurgitation. She underwent urgent surgery and third time sternotomy was performed. CPB was established by cannulating left femoral artery and vein. Prior to the second redo sternotomy, left groin was exposed and femoral artery and vein were exposed, and purse-strings were taken. Sternotomy was performed; then, heparin was given, and cannulation was done.

Fig. 2.

Contrast CT scan (axial view): arrow showing recurrence of pseudoaneurysm on the proximal aorta lateral to the previous patch

During sternotomy, innominate vein and pseudoaneurysm were inadvertently injured during sternotomy and CPB was established by promptly cannulating femoral vessels. Patient was cooled and deep hypothermic circulatory arrest was achieved to control the bleeding. There were no obvious features of the infection on aortic tissue. She underwent aortic root replacement using 25 Magna Ease prosthetic valve stitched in a Gelweave tube graft (30 mm) and coronary buttons were stitched on the graft. Distal end on this graft was anastomosed to the previous tube graft. Patient was bleeding after the surgery and went back to theatre for the re-exploration and control of the bleeding. Aortic tissue culture grew Corynebacterium aurimucosum and she was treated with antibiotics (vancomycin and doxycycline) for the next 6 weeks. After 10 days of in-hospital stay, patient was discharged home but she was re-presented after 2 weeks with fluid collection around the prosthetic tube graft on CT scan (3 × 2 cm). This collection was homogenous, non-fibrinous and well defined on CT scan. Echocardiography showed fluid around the graft but there were no cardiac tamponade and patient was managed conservatively. At 6-month follow-up, patient is doing fine with improving periprosthetic collection.

Discussion

Various techniques like, tube graft replacement, root replacement, synthetic graft patch or direct suture closure of the defect, have been reported in the literature to manage aortic pseudoaneurysm [2]. Historically quoted incidence of pseudoaneurysm is below 0.50% but with increasing radiological surveillance, rate of incidental positive findings is on the rise [3]. Causative mechanisms for its formation are trauma, infection, connective tissue disorder, aortic dilatation, auto immune diseases, tuberculosis, foreign bodies in the oesophagus causing fistulous connections and suture dehiscence [4]. Our patient had no features of connective tissue disorder, but the manner in which aortic pseudoaneurysms were recurring and expanding was indicative of an uncommon infection. First presentation of pseudoaneurysm might be caused by weak native aortic tissue but she had two episodes of high-grade fever 1 month post-surgery and raises suspension of low-grade infection. Her second pseudoaneurysm presentation was more in-line with mycotic presentation because of the rate of increase in the size and its shape on CT scan. Features in the favour of late mycotic pseudoaneurysm were fast size expansion, saccular configuration and involvement of native aorta rather than aorto-graft anastomosis dehiscence [5]. Mycotic aneurysms and pseudoaneurysms are responsible for high mortality and prompt diagnosis and treatment are paramount.

During first redo surgery, only patch repair was performed because the rest of the aortic tissue looked clean and relatively strong. Other reasons for not doing aortic root replacement were normally working tricuspid aortic valve, non-effaced aortic root and normal size ascending aorta. Obviously, we thought pros and cons of root replacement and decided in the favour of just patch as there was no infective tissue seen. Pseudoaneurysm formation after previous cardiac surgery can happen because of the degenerative or infective pathology. Most common sites are anastomotic suture lines and cannulation sites, but in the cases of aortic dissection and infection, it might erupt anteriorly on the ascending aorta (near the STJ). Our case had similar location first time, and on second occasion, it was more laterally on the ascending aorta, but at the same level (Fig. 3). Aortic root replacement was performed at third surgery because of moderate aortic regurgitation and poor-quality thinned-out aortic tissue. During re-operations, proper cardioplegia delivery, perfect attachment of the coronary buttons to the graft and avoiding left ventricular distension are major factors for good immediate outcomes. Involvement of sinus of Valsalva, distal aorta and coronary ostia increases complexity of the surgery and overall results. One of the key considerations in surgical intervention is choosing an approach that allows safe re-entry into the chest and minimizes the risk of catastrophic haemorrhage from pseudoaneurysm rupture. The risk of pseudoaneurysm rupture depends on whether the pseudoaneurysm is anterior or posterior to the aorta and the distance from the sternum [5]. If the pseudoaneurysm is anterior and situated less than 2 cm from the sternum, the patients are considered at high risk for re-entry and cardiopulmonary bypass should be established before re-sternotomy. The risk of pseudoaneurysm rupture is less for anterior pseudoaneurysms 2 cm or more from the sternum and for posterior pseudoaneurysms. The mortality rate of aortic root pseudoaneurysm has been reported to be between 6.7 and 60%, which may vary depending on the age of the patients, clinical presentations and associated comorbidities.

Fig. 3.

Contrast CT scan (volume-rendered image): second recurrence of pseudoaneurysm seen laterally to the previous patch

The most common location for post-operative pseudoaneurysms is the graft anastomosis site followed by the coronary artery anastomosis site, aortotomy site, aortic cannulation site and needle vent site [6]. Proximal anastomosis involvement is higher than distal graft anastomosis and anterior aspect of the aorta is more commonly involved compared to the posterior aspect of the aorta. Due to the rare occurrence and inconsistent reporting, natural history of these pseudoaneurysms is not well known, but they have potential to cause symptoms and haemodynamic instability with increase in the size. Most of the patients who declined surgical treatment survived up to 23 months [6].

On the CT scan, the sinus of Valsalva aneurysm appears as an asymmetric saccular dilatation with normal dimensions of the adjacent aortic root and ascending aorta as opposed to a pseudoaneurysm, which appears as a focal outpouching of contrast enhancement that is separate from the sinuses of Valsalva (Figs. 2 and 3). For instance, the presence of periaortic fluid in the form of stranding (fluid mixed with fat, no clear borders and completely encircling the aortic graft) in the first 3 post-operative months can be considered a normal finding, even when it extends up to 17 mm in the dimension [7]. Our case also had significant post-operatively peri-graft fluid collection and it was managed conservatively. Because of these frequent post-operative changes, radiological recommendations are 3-month, 6-month and then yearly follow-up after the surgery using cardiac-gated CT scan and 3-dimensional reconstruction [8].

Surgery is the treatment of the choice and percutaneous interventions are offered in the patients those who are very high risk of open-heart surgery. Endovascular intervention (EVI) is contraindicated in patients with infective pathology, pseudoaneurysm closure to the coronary ostia and aortic valve, rapidly expanding neck, compression of the surrounding structures and suspected free rupture. In selected cases, various EVI techniques were reported with the use of stent grafts, coil embolization, thrombin injection, or Amplatzer septal occluders (St Jude Medical, USA) [9]. These techniques are restricted to the high-risk patients, who already had multiple sternotomies in the past and have other severe comorbidities. For the successful outcome following EVI, sizing of the pseudoaneurysm neck is of paramount and various modalities like intravascular ultrasound (IVUS) and contrast CT scans are used for this purpose. Because of rarity of pseudoaneurysm occurrence, there are no large reports where surgery is compared to the endovascular options. More than 90% of publications are case reports and most recent study of EVI had just seven cases. EVI can be difficult for the ascending thoracic aorta lesions because of many logistical issues, like proximity of the aortic valve, coronary ostia, aortic branch arteries, aortic curvature and inability to reach in long patients from femoral arterial access. Preventza et al. had reported importance of arterial access for successful EVI need meticulous planning and ideal place to perform these high-risk interventions is a hybrid operating theatre to deal with any procedural mis-happening [10]. Concerning findings after EVI are device dislodgement, persistent residual shunt after 6 weeks and continuous expansion of the pseudoaneurysm.

Conclusion

This case reinforces the importance of early diagnosis and aggressive surgical management of expanding ascending aortic pseudoaneurysms without leaving behind any weak and pathological aortic tissue at the time of surgery.

Funding

No funding received.

Compliance with ethical standards

Ethics committee approval

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Conflict of interest

None.

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Informed consent

Patient’s written consent was taken.